1. Field of the Invention
The present invention relates generally to freeze protection, fire protection and environmental control systems.
2. General Background of the Invention
Many buildings today have sprinkler systems therein for fire protection. These sprinkler systems usually comprise a piping system located in an air space above a drop ceiling, and a number of sprinkler nozzles extending below the drop ceiling. The drop ceiling usually has good insulating and fire-resisting values, and thermally separates this upper air space from the air space below the ceiling which, in most areas, is heated in the winter and cooled in the summer. In colder climates, where the temperature outside the building often drops below freezing during the winter, there is the danger that the water in the piping system will freeze, rendering the sprinkler system inoperable, and making the building especially vulnerable if a fire should break out while the system is frozen. In addition, frozen water pipes can be extremely disadvantageous even if no fire breaks out, because the water, which expands as it freezes, may burst the pipes. When the ice in the pipes thaws out, allowing water to escape from the broken pipes, severe water damage can occur to the building and to its contents.
Various methods have been used to attempt to keep the water in sprinkler systems, in the upper air space above drop ceilings, from freezing. One method is to insulate the piping--this may be effective if the air in the upper air space drops below freezing only briefly. However, since insulation only slows the transfer of heat, if the temperature of the upper air space should stay below freezing for any extended period of time, the water in the pipes will freeze.
Another method currently in use is to install a circulation pump in the sprinkler system. These pumps usually circulate water in the main line only, leaving branch lines unprotected against freezing.
Heaters are sometimes installed in the upper air space above the drop ceiling. In most states, however, this constitutes a violation of fire codes.
Another method of protecting sprinkler systems from freezing involves removing a number of ceiling tiles from the drop ceiling, thereby allowing the warm air below the ceiling to rise into the air space above the ceiling. Some persons do this only when a freeze is anticipated, while others remove a number of ceiling tiles when the winter begins, and do not replace them until all danger of freezing is over for the year. While both of these last-mentioned methods are effective at keeping the sprinkler system from freezing, the disadvantages of such methods far outweigh the advantages. In the case where the tiles are removed for the duration of the winter, a tremendous amount of energy is wasted, as the upper air space is heated whether the temperature outdoors is below freezing or not. In the case where the tiles are removed only when a freeze is anticipated, a sudden unpredicted drop in temperature can catch the building operator unaware, and cause the pipes to freeze. In both cases, the fire rating of the ceiling is lost, fire insurance may be voided, and, in most locations, removal of ceiling tiles is a violation of the fire code.
In view of the potential hazards which occur when sprinkler systems freeze, and the various inadequate, unsafe and/or prohibited methods mentioned above now employed to prevent sprinkler systems from freezing, it can be seen that there exists a need for a safe, economical, effective system to prevent sprinkler systems in buildings from freezing.